Database Instance

What is Schema?

The Skeleton of the database is created by the attributes and this skeleton is named Schema. Schema mentions the logical constraints like table, primary key, etc. The schema does not represent the data type of the attributes....

Database Schema

A database schema is a logical representation of data that shows how the data in a database should be stored logically. It shows how the data is organized and the relationship between the tables. Database schema contains table, field, views and relation between different keys like primary key, foreign key. Data are stored in the form of files which is unstructured in nature which makes accessing the data difficult. Thus to resolve the issue the data are organized in structured way with the help of database schema. Database schema provides the organization of data and the relationship between the stored data. Database schema defines a set of guidelines that control the database along with that it provides information about the way of accessing and modifying the data....

Types of Database Schemas

There are 3 types of database schema:...

Creating Database Schema

For creating a schema, the statement “CREATE SCHEMA” is used in every database. But different databases have different meanings for this. Below we’ll be looking at some statements for creating a database schema in different database systems:...

Database Schema Designs

There are many ways to structure a database, and we should use the best-suited schema design for creating our database because ineffective schema designs are difficult to manage & consume extra memory and resources....

Difference between Logical and Physical Database Schema

Physical Schema Logical Schema Physical schema describes the way of storage of data in the disk. Logical schema provides the conceptual view that defines the relationship between the data entities. Having Low level of abstraction. Having a high level of abstraction. The design of database is independent to any database management system. The design of a database must work with a specific database management system or hardware platform. Changes in Physical schema effects the logical schema Any changes made in logical schema have minimal effect in the physical schema Physical schema does not include attributes. Logical schema includes attributes. Physical schema contains the attributes and their data types. Logical schema does not contain any attributes or data types. Examples: Data definition language(DDL), storage structures, indexes. Examples: Entity Relationship diagram, Unified Modeling Language, class diagram....

Advantages of Database Schema

Providing Consistency of data: Database schema ensures the data consistency and prevents the duplicates. Maintaining Scalability: Well designed database schema helps in maintaining addition of new tables in database along with that it helps in handling large amounts of data in growing tables. Performance Improvement: Database schema helps in faster data retrieval which is able to reduce operation time on the database tables. Easy Maintenance: Database schema helps in maintaining the entire database without affecting the rest of the database Security of Data: Database schema helps in storing the sensitive data and allows only authorized access to the database....

Database Instance

The database schema is defined before the actual database is created, after the database is operational, it is very difficult to modify the schema because the schema represents the fundamental structure of the database. Database instance does not hold any information related to the saved data in database. Therefore database instance represents the data and information that is currently stored in the database at a specific point in time....

Conclusion

The Structure of the database is referred to as the Schema, and it represents logical restrictions like Table and Key, among other things. Three Schema Architecture was developed to prevent the user from direct access to the database. Since the information that is saved in the database is subject to frequent change, Instance is a representation of a data at a specific time....